Your mission, should you choose to accept it, is to read the following case history, identify the parasite, and answer any bonus questions. I'll start you off with an easy one.

Identify That Parasite!!!

Some of your sheep have started sneezing. Additionally, some of the sheep have been shaking their heads and stamping their feet. On physical exam, the affected sheep have serous-to-mucopurulent nasal discharge. You bust out your flashlight (nerd) and spot this nasty little bugger wriggling in one of the sheep's nasal passages (see image below). You scream in disgust/ delight! Which of the following is the identity of the parasite?

Correct Answer:(D) Oestrus ovis (aka., sheep nose bot fly, sheep nasal fly, sheep bot fly). The larval stages of O. ovis develop in the nasal cavity of sheep and goats. While in flight, the adult flies deposit the larvae directly into or around the nostrils. Click here for additional images of Oestrus ovis.

Incorrect Answers:(A) Gasterophilus nasals - This is the throat bot fly of horse.(B) Trichuris ovis - This is the sheep whipworm.(C) Hypoderma ovis - This is the warble fly of cattle.(E) Dermatobia hominis - This is the human bot fly.

Bonus Answer:Ivermectin (200 mcg/kg, PO or SC, once) is the treatment of choice. This therapy is highly effective against all stages of the larvae.

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